When in doubt always check the Options:
In[9]:= Options[HorizontalGauge]
Out[9]= {AlignmentPoint -> Center, AspectRatio -> Automatic,
Axes -> False, AxesLabel -> None, AxesOrigin -> Automatic,
AxesStyle -> {}, Background -> None, BaselinePosition -> Automatic,
BaseStyle -> {}, ColorOutput -> Automatic,
ContentSelectable -> Automatic, CoordinatesToolOptions -> Automatic,
DisplayFunction :> $DisplayFunction, Epilog -> {},
FormatType :> TraditionalForm, Frame -> False, FrameLabel -> None,
FrameStyle -> {}, FrameTicks -> Automatic, FrameTicksStyle -> {},
GaugeFaceElementFunction -> Automatic, GaugeFaceStyle -> Automatic,
GaugeFrameElementFunction -> Automatic, GaugeFrameSize -> Automatic,
GaugeFrameStyle -> Automatic, GaugeLabels -> None,
GaugeMarkers -> Automatic, GaugeStyle -> Automatic,
GridLines -> None, GridLinesStyle -> {}, ImageMargins -> 0.,
ImagePadding -> All, ImageSize -> Small, ImageSizeRaw -> Automatic,
LabelStyle -> {}, Method -> Automatic,
PerformanceGoal :> $PerformanceGoal, PlotLabel -> None,
PlotLegends -> None, PlotRange -> All, PlotRangeClipping -> False,
PlotRangePadding -> Automatic, PlotRegion -> Automatic,
PreserveImageOptions -> Automatic, Prolog -> {}, RotateLabel -> True,
ScaleDivisions -> Automatic, ScaleOrigin -> Automatic,
ScalePadding -> Automatic, ScaleRanges -> Automatic,
ScaleRangeStyle -> Automatic, ScalingFunctions -> None,
TargetUnits -> Automatic, Ticks -> Automatic, TicksStyle -> {}}
So here is a possibility:
HorizontalGauge[55, {0, 100}, ImageSize -> 400, BaseStyle -> 14]